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Where is the canvas javascript code written?
- PHPzOriginal
- 2023-04-25 09:14:11457browse
Canvas is a new feature of HTML5, which can be used for drawing operations through JavaScript. So, where should we write the canvas-related JavaScript code?
Generally speaking, canvas-related JavaScript code should be written in the <script></script> tag of the HTML file, or referenced in a separate JavaScript file. Specifically, this can be achieved through the following steps:
- Create HTML file: First, we need to create an HTML file, which can be created through a text editor or IDE and other tools. The specific code is as follows:
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>画布JavaScript代码示例</title> </head> <body> <canvas id="myCanvas"></canvas> <script src="js/canvas.js"></script> </body> </html>
This is a simple HTML file, which contains a <canvas> tag and a <script> tag. The <canvas> tag is used to display the canvas, and the <script> tag is used to reference the JavaScript file.
- Create JavaScript file: In the above HTML file, we referenced a JavaScript file named
canvas.js. Therefore, we need to create thecanvas.jsfile in the project and write the canvas-related code in it. The specific code examples are as follows:
// 获取canvas元素
let canvas = document.getElementById('myCanvas');
// 获取canvas上下文
let ctx = canvas.getContext('2d');
// 绘制矩形
ctx.fillStyle = 'orange';
ctx.fillRect(10, 10, 100, 50);
// 绘制圆形
ctx.fillStyle = 'green';
ctx.beginPath();
ctx.arc(150, 35, 25, 0, 2 * Math.PI);
ctx.fill();
// 绘制文本
ctx.fillStyle = 'blue';
ctx.font = '20px Arial';
ctx.fillText('Hello World!', 200, 35);
The above code is used to draw an orange rectangle, a green circle and a blue text. Among them, the getContext() method is used to obtain the canvas context, and drawing operations can be performed through the context object.
- Reference the JavaScript file in the HTML file: After the above two steps are completed, we need to reference the JavaScript file written in step 2 into the HTML file. The specific code is as follows:
<script src="js/canvas.js"></script>
After adding the above code to the HTML file, the browser can load and execute the JavaScript code in the canvas.js file to realize the canvas drawing function. .
In short, for canvas-related JavaScript code, we can reference it through the <script> tag or a separate JavaScript file to achieve canvas drawing. Correctly referencing JavaScript files is one of the keys to ensuring the normal operation of JavaScript code.
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